Monday, April 26, 2010

Livewell Timer Circuit - Simple Recycle Timer

I updated my livewell timer design originally made in 2004 for my previous boat. I have yet to find another livewell timer circuit on the internet so I figured I'd put mine up on the blog. All the parts should be available at any Radio Shack. The circuit features a manual fill override, 30 or 60 second switched On Time and 1-8 Minutes infinitely variable Off Time. The 555 timer must be a CMOS low power version to get these long of delays and the relay should be rated at 5 amp or better. The motor is only rated ar 2 amp but it's an *inductive load* while relays are rated for a resistive load necessitating a higher amperage relay to keep from burning the contacts from inductive kickback. The main difference between the new circuit and the old one is the addition of a selectable on time so this circuit has been field tested and proved 100% reliable over the last 6 years.

On my last boat I also added a Pulse Width Modulator motor speed control to control the water flow/pressure. The smallest livewell pump available is 500 gallons per minute which is way overkill for smaller livewells. The spray head restricts it somewhat and the common solution is to insert a valve in the line and choke it down which wastes a lot of electricity. So a 50% duty cycle from the PWM will cut your amp hour usage nearly in half ( There are circuit loses keeping us from a full 50% savings) Again the circuit is simple and the parts available at any Radio Shack. (I don't get my parts there all that often but I like to design with Radio Shack available parts so I can repair a circuit ASAP, there is always a Radio Shack fairly close by) If I do decide I need it I'll go dig out the schematic and post it on the blog.

It'll probably be a week yet before I get back to the Netbook to Chartplotter, getting my new boat on the water is a priority (This project isn't much good without a boat to test it in). I did get a Ram Mount and their Tough Tray II universal netbook/tablet PC mount which will give me the ability to rotate the computer to the front where I can see it while operating the trolling motor. Right now I'm putting the finishing touches on the design of the electronics package and I'll start pulling the wires and doing the 'rough in' so I can get the floors in and start the painting process.

1 comment:

Trolling Motors said...

Hello J.R.,

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More power and keep me posted!